[Paul C]

Hi,

I have a 2003 BMW 316i SE (E46). And last week I was doing normal checks as I was going on a long trip and I noticed that the coolant was very low even though the light never came on. When I went to get some coolant, THEN the light came on, kinda flickering on and off.

I put 1L of coolant in and I left the car for the night.
The next morning as I was driving the work I noticed the coolant light was still on (constantly this time). When I got to work, I waited for the car too cool for a few mins (its only 4 miles to work) and then checked the coolant level, and it was at the very bottom. I went to the petrol station after work and put another 1L of coolant in (each time I put coolant in, it brought the gauge up to mid or full level).

I brought it to a garage and the mechanic said he couldn't find a leak but he put some stuff in that will patch up leaks if there were any.

The light has stayed off since, but today I went for a trip and after I checked the engine and I could hear a whistling sound (like air escaping) coming from the engine.

Any ideas what it could be?
2L's of coolant can't just disappear can it?
And the whistling?


Regards,
Paul

 

[John_D]

Generally leaking coolant will leave white stains, have a good look around all your coolant pipes and expansion tank. plastics can get quite brittle with age and eventually crack and split.

As for the whistling, is that while its running or after it stops or both ?
could be many things including PCV.

check also the two rubber o-rings on your expansion tank cap, if they are old and flat the cooling system wont pressurise properly and can boil over possibly causing this whistling you hear.

 

[Rich]

Have a look under the bonnet while its hissing and see if you can pinpoint it. The expansion bottle is a common failure and sometimes will only leak when running and under pressure. There's a plastic pipe at the back of the engine that can often crack and leak too.

Have you still got heating?

 

[rebel.ranter]

The thermostat housing can get brittle & leak, maybe the whistling is the water/steam making its way out?
BTW, I wouldn't be happy with anyone putting "magic potions" in to my engine.

 

[ChrisE46]

Had a similar situation in my own yoke a few months back. Turned out it was the expansion tank, i couldnt see any leaks as one of the pipes was blocking my view. Jack the car up, take off the plastic and get comfortable! Leave the car running for a few minutes and search all over the expansion tank for a leak. Maybe throw down some newspaper to give you a general idea of where its coming from.Give some of the pipes around the tank a squeeze, this may help you find the leak.

Generally if it is the tank, it will be either the seams down the sides or the top section that will pop.

Also the cap on the tank is pressurised, if your coolant system has been airlocked or built up pressure the cap could have blown. Could be a nice cheap fix.

 

[maciejowy1987]

Expansion cap I`d say :/
Wrecked my head at some stage as well (it opens and it shouldn`t, made a kettle effect and in time coolant was evaporating :/)
Took some time (and lot of reading!) to figure it out.

I`d say borrow or get a cap as its the cheapest start to troubleshoot?

 

[John_D]

Oh and to save you the trouble, a new cap from the dealer when I bought one was actually cheaper than any aftermarket parts I looked at so no excuses not to get a genuine one

 

[dubinkildare]

The above is all spot on. Coolant system is a weak point so eventually your looking at water pump, rad, thermostat and expansion tank. With a bit of luck it might be the expansion tank cap, although you would see white residue in and around the side/top of expansion tank. I've had to replace thermostat and expansion tank in last few months. My advice is to just get it pressure tested. Should'nt cost more than 50 from a local Indy and he'll be able to tell you what the problem is straight away. I presume the car isn't overheating?

Sent from my HTC Sensation Z710e using Tapatalk 2

 

[stoney5123]

Another common spot for leaks is the plastic elbow on the back of the head. You'll need to remove the pollen filter & housing to get to it. Have replaced loads of these over the years. New part is only €13 euro or so from BMW. Hope this helps

 

[Rich]

Another common spot for leaks is the plastic elbow on the back of the head. You'll need to remove the pollen filter & housing to get to it. Have replaced loads of these over the years. New part is only €13 euro or so from BMW. Hope this helps

That's exactly the bit I was referring to above, very common for them to fail.

 

[danlolasdad]

overhaul the cooling system if its a daily driver i done one recently that had been pissed about with by idiots and its mint now. rad blocked, cap damaged, expansion bottle cracked, waterpump plastic impeller in shit, stat/housing broken, hoses perished and the plastic elbows were all turned to jelly car had water in it not coolant. i had to collect car but put coolant in it and it showed up everywhere. im amazed the gasket in a bmw took this abuse but it did win ;-P. the secondary air system pump was also blowing itself apart at the seams as the alloy rivets were puling apart that was an easy fix vaccum pipes are crap quality too i used some leftover silicone ones from another job id completed. some paats will be from factors like pump with upgraded steel impeller the dealers dont do one

 

[stoney5123]

overhaul the cooling system if its a daily driver i done one recently that had been pissed about with by idiots and its mint now. rad blocked, cap damaged, expansion bottle cracked, waterpump plastic impeller in shit, stat/housing broken, hoses perished and the plastic elbows were all turned to jelly car had water in it not coolant. i had to collect car but put coolant in it and it showed up everywhere. im amazed the gasket in a bmw took this abuse but it did win ;-P. the secondary air system pump was also blowing itself apart at the seams as the alloy rivets were puling apart that was an easy fix vaccum pipes are crap quality too i used some leftover silicone ones from another job id completed. some paats will be from factors like pump with upgraded steel impeller the dealers dont do one

I second this. Have replaced everything bar the radiator & the problem seems to be cured. Plastic pipe under the inlet manifold is a bit of a pain to get to but mine had crumbled so needed doing

 

[danlolasdad]

strip off all the intake its the only way get the power washer going and wash away any crap while its stripped too i need to update this album before doing a thread



http://s250.photobucket.com/albums/gg269/twincamdan/ERICAS CAR/?start=all

 

[tommyboy40]

That's exactly the bit I was referring to above, very common for them to fail.

Did it on my own, took ages to figure out it was leaking here. Big hissing sound

 

[cambo e46]

if the exspansion bottle is cracking theres usually an explanation,,

most people just replace bottle and then 3 months end up doing it again ,
id put it down to waterpump id change the lot ,pump,termo, exspansion botle